The Effect of Flame Retardants on Thermal Degradation of alpha-Cellulose in Nitrogen

摘要

Measurements for use in assessing the Parker-Lipska model for decomposition of cellulose are reported. These include changes in molecular weight during isothermal pyrolysis and increases in char yield and weight-loss rate due to retardant treatment. These experiments also investigated the role of 1,5-anhydro-2,3-deoxy-beta-D-pent-2-enofuranose (a major product of thermally degraded cellulose and levoglucosan) in the char-formation process of fire-retarded cellulose. The isolated furanose derivative, both in the neat form and in the presence of NH4H2PO4, was pyrolyzed and its degradation products were analyzed by means of a gas chromatograph. At 276C, initial pyrolysis of alpha-cellulose results in an abrupt decrease in average molecular weight and is followed by a linear decrease over a prolonged period of heating. Increased yields of char and rates of degradation due to the basic and neutral retardants were found to be in quantitative agreement with the predictions of the Parker-Lipska model for decomposition of cellulose. The results of the pyrolysis experiments on the furanose derivative support the contention that the excess yield of char in retardant-treated cellulose is due to the degradation of secondary products of cellulose decomposition rather than of the cellulose molecule itself. (Author)